The Fishes ( Pisces )
The fishes are the last class of the vertebrated animals, and have cold, red blood. The elongated body generally tapers off to the tail; the head and neck are large; the limbs are called fins, and are such as to make efficient paddles. They are usually one or more fins in the middle line of the back and one or two in a corresponding position beneath the tail (anal fins); while the tip of the tail is terminated by a caudal fin, the chief organ of swimming. All of the fins are supported by a skeleton of rays, either horny or spinous in character.
There are but two chambers to the heart, and the occurrence of a swim bladder, an organ for regulating or recognition of the depth of the water in which the fish is, is very frequent. Externally fish have a defensive armor of scales or bony plates embedded in the skin. They breathe throughout life by means of gills, which are delicate folds or filaments connected with openings (gill slits) in the sides of the throat. The fishes live in water, and reproduce their species by eggs.
There are several great groups of fishes, distinguished by the presence of a cartilage or bony skeleton, by having the gill slits free or under a gill cover, by characteristics of the skull, presence or absence of air bladder, and by peculiarities of the digestive tract and nervous system.
(1) The bony, or true fishes (Teleostei), which include all the most familiar freshwater and marine forms; (2) the Cartilaginous fishes (Elasmobranchii), including sharks, dog-fish, bays and skates; (3) the heavily-armored fishes (Ganoidei), like the sturgeons and bony pike; and (4) the double-breathers (Dipnoi), of rare occurrence.
The Bony Fishes ( Teleostei )
These have a bony skeleton, and a well-defined vertebra, or backbone; their bodies are mostly covered with scales.
Alewife (Alosa tyrannus), a fish of the same genus with the Shad, which, at the beginning of summer, appears in great numbers on the east coast of North America, and enters the rivers to spawn. It appears in Chesapeake Bay in March, on the coasts of New York and New England in April, and on those of the British provinces about May 1. It abounds in the bay of Fundy, but is more rare in the gulf of St. Lawrence; and the bay of Miramichi appears to be its northern limit. Its length is not more than twelve inches. The alewife is called spring herring in some places, and gaspereau by the French Canadians.
Bass (Labrax) is a member of the perch family. The shape is salmon-like. The color is without the zebra-like bars of the perch, and shades off from dusky blue above to silvery white beneath.
The Striped Bass or Rock-fish of the United States (L. lineatus) very nearly resembles the common bass, but attains a larger size. It is one of the most important of American food fishes, and sometimes weighs fifty pounds. It is caught from July to September. The name Stone Bass is given to various forms. A Yellow Bass is found in the Lower Mississippi valley, and the Fresh-water Bass is an imported fish found in the streams of eastern New York and the other middle states.
Bluefish (Temnodon or Pomatomus saltator).—A fish common on the eastern coasts of America, allied to the mackerel. The only known species is abundant on the east coast of North America. The upper parts are of a bluish color, the lower parts whitish, a large black spot at the base of the pectoral fins. The mouth is crowded with teeth, the jaws are furnished with large ones. The bluefish preys on other fishes, such as the menhaden and mackerel, the shoals of which it pursues. It sometimes attains a length of three, or even five feet, and a weight of fourteen pounds. It is often caught by trolling, as it bites readily at an object drawn swiftly through the water. It is much esteemed for the table.
Bullhead.—In the United States the name is given to some species of catfish or horned pout; in England to a smaller fish, allied to our miller’s thumb, but belonging to a different group from the catfish.
Carp. See page 256.
Cod (Gadus), a genus of bony fishes in the soft-rayed order. This is probably the most important food fish and is taken in enormous numbers on the coasts of Europe and of eastern North America. It occurs in the northern Pacific as well. It feeds upon other fishes as well as on shellfish, and large specimens weigh over one hundred pounds. Allied to the cod are the haddock, pollack, hake and cusk.
Eel (Anguilla vulgaris) has elongated form, and has become proverbial on account of its slipperiness and tenacity of life. In the rivers and lakes only female fish are found; the males keep to the open sea. The former go down to the sea in the autumn; but in the following spring the young female fish swim up the rivers in immense numbers, while the young males remain in the sea. During the day the eel conceals itself in the mud, but at night it exhibits its voracious qualities by swallowing numerous fish, water insects, crabs, mussels, and worms. Its firm, delicate flesh is much esteemed.
Flounder (Pleuronectes flesus), a common species of flat-fish, of wide distribution in shallow waters in north temperate countries. It is the Scotch “fluke,” and the Swedish “flundra,” and differs but a little from the plaice and dab, two of the commonest neighbor-species. Like other flat-fishes, the flounder is asymmetrical, and swims or rests on one side, almost always the left, the eye of which is in early youth, brought round to the upturned surface. It measures about one foot in length, and about a third as much between the dorsal and the ventral edge, without including the fringing fins.
Of the two dozen related species, the plaice, the dab, the smear-dab, and the craig-fluke are the commonest.
Flying-fish.—Various fishes which have the power of sustaining themselves for a time in the air by means of their large pectoral fins. Generally, however, the name is limited to the species of the genus Exocoetus, which belongs to the family of mackerel-pikes. These can pass through the air to a considerable distance, sometimes as much as two hundred yards, to escape from the attacks of other fishes, especially the dolphin. They are most common between the tropics.
Goldfish. See page 256.
Haddock (Gadus æglefinus) is a fish of the same genus as the cod, and much resembling it in general appearance; but distinguished by a notched tail and a white line along the side. In habits the two are much alike, being voracious, eating anything edible, but largely clams and the like.
Halibut (Hippoglossus vulgaris), the largest of all the flat-fish and in form more elongated than the flounder or the turbot. The halibut, though esteemed for the table, is not to be compared in quality with the turbot; its flesh is white and firm, dry and of little flavor. It attains a great size; specimens have been caught weighing at least five hundred pounds, and one caught in Iceland was little short of twenty feet long.
Herring (Clupea harengus) belongs to the order of bony fishes and is spread over the whole North Atlantic. It is of great economic importance, and occurs in large schools, swimming through the sea with open mouths, scooping up the minute life for food. Immense numbers are taken both here and abroad, the annual catch for Europe and America being estimated at a billion and a half pounds. The young are also taken in vast quantities and are preserved as American sardines. With us most of the adults are smoked and dried.
Mackerel (Scomber), a genus of fishes which also includes the tunny, bonito, and sucking fishes. It is an important food fish occurring in the North Atlantic and characterized by its slender shape, the series of little finlets on the tail and the deeply notched caudal or tail fin. It is taken both by hooks and by seines. Some are eaten in the fresh condition and some are salted. It goes in large schools. Allied is the Spanish mackerel of our southern waters and the large horse mackerel which is more common in the Mediterranean, where it is called the tunny.
Perch (Perca).—Spiny-finned fishes, well represented by the Fresh-water Perch (P. fluviatilis), which is widely distributed in lakes, ponds, and rivers in Europe, Northern Asia, North America and Britain. It is of a greenish-brown color above and golden yellow on the under parts, with six or seven indistinct dark bands on the back. In length it measures about eighteen inches, and its height is about a third of this. It sometimes weighs from three to five pounds, and a prize of nine pounds has been recorded.
Porgy.—A food fish on the eastern coast from Cape Cod south, known also as scup. It should not be confounded with the pogy or [227] menhaden, one of the herrings, which is taken extensively for oil.
Pollack (Gadus pollachius), a fish, belonging to the cod genus. It is about the size of the coal-fish, is active in habit, and is frequently caught. The lower jaw projects beyond the upper, and there is no barbel. It has commercial value in the English Channel and off the coasts of Newfoundland. Allied species, which promise a valuable future, abound from Puget Sound to Alaska on the Pacific coast.
Salmon (Salmo), a genus of well-known fish which inhabits both salt and fresh waters, and ranks among the food-fishes. It generally attains a length of from three to four feet, and an average weight of from twelve to thirty pounds, but these limits are frequently exceeded. The adult fish is a steel-blue on the back and head, becoming lighter on the sides and belly.
It usually continues in the shallows of its native stream for two years after hatching, and during this period it attains a length of eight inches. When the season of its migration arrives, the fins have become darker and the fish has assumed a silvery hue. It is now known as a smolt or salmon fry. The smolts now congregate into shoals and proceed seaward. On reaching the estuary they remain in its brakish water for a short time and then make for the open sea. Leaving its native river as a fish weighing, it may be, not more than two ounces, the smolt, after three months’ absence, may return to fresh water as a grilse, weighing four or five pounds. In the grilse stage, the fish is capable of depositing eggs. After spawning in the fresh water the grilse again seeks the sea in the autumn, and when its second stay in the ocean is over it returns after a few months’ absence as the adult salmon, weighing from eight to ten pounds. The salmon returns as a rule to the river in which it passed its earlier existence. The fertility of the fish is enormous.
Salmon are caught by the rod, and by means of nets, the fishings being regulated by law. There are important fisheries in some European and North American rivers. In Europe the fish is found between the latitudes of forty-five and seventy-five degrees, in North America in corresponding latitudes. The flesh when fresh is of a bright orange color, and is of highest flavor when taken from the sea-feeding fish. In the waters of northwestern America are several salmon belonging to a distinct genus, including the quinnat or king-salmon, blue-back salmon or redfish, silver salmon, dog salmon, and humpback salmon. The quinnat has an average weight of twenty-two pounds, but sometimes reaches one hundred pounds. Both it and the blue-back salmon are caught in immense numbers in the Columbia, Sacramento, and Frazer rivers (especially in spring), and are preserved by canning.
Sardine, or Pilchard (Clupea pilchardus) is an important fish closely related to the herring and sprat. In size it grows from ten to fourteen inches; in color it is bluish-green above, whitish underneath and on its sides. It is entirely marine in habit, and its eggs float on the surface of the sea, unlike those of the herring, which are attached to objects at the bottom. The young, before it has attained maturity, is known as the sardine, and as such forms a valuable fishery; the full-grown pilchard is used as an article of diet as well as for bait. The method of capture is usually by drift-net. It is most abundant off the coasts of Portugal, and in the English Channel and the Mediterranean.
Shad is a migratory fish of great food value. It ascends all of the rivers of the eastern coast of the United States every spring to lay its eggs. It is closely related to the herring, but is much larger, and were it not so full of bones it would stand very near the head of food fishes.
Smelt (Osmerus) is a genus of the Salmon family, characterized by strong fang-like teeth, and by rather large scales, which readily fall off. The form is very trout-like, but rather more slender; the tail is larger in proportion, and more forked. The back is whitish, tinged with green; the upper part of the sides shows bluish tints, the lower part of the sides and the belly are of a bright silvery color. The smelt has a peculiar, cucumber-like smell, and a delicious flavor, on account of which it is highly esteemed for the table.
Sole (Solea) is a fish oval in shape, the outline of the snout being semi-circular, and projecting somewhat beyond the mouth. The Common Sole (S. vulgaris) is a fish of high value in European markets. It lives in European seas from the Mediterranean to the north of Denmark, and is rarely caught on the American side of the Atlantic Ocean, although numerous closely allied kinds abound.
Sword-fish (Xiphiidae) are abundantly represented in tropical and subtropical seas. They are among the largest bony fishes, sometimes measuring twelve to fifteen feet in length. The sword, which may be over three feet long, is formed from a compressed prolongation of the upper jaw, and is often strong enough to stab whales fatally, or less advantageously to pierce the bottom of a ship or the planks of a boat. Sword-fish are said to attack whales and other cetacea, and also boats and canoes, and even large vessels.
Trout, a name applied to various members of the Salmon family. The Common or Brown Trout (Salmo fario) varies greatly in appearance, not only with individuals but at different seasons, and this variability has led some authorities to distinguish a number of subspecies.
At midsummer an adult trout is usually brownish or olive in color, with pure white on the belly and gold on the flanks, while the back varies from olive or pale brown to nearly black. The dorsal fin and sides are spotted with black and often also with scarlet. The scales are circular, thin and minute. When the spawning season begins in autumn all the color disappears and the body becomes slimy to the touch. The head of the male is larger than that of the female, and the lower jaw bears a cartilaginous knob. It feeds on a large variety of food, different kinds appealing in turn. It is by cunning imitations of some prevailing fly that the fisherman makes his most cherished captures.
The artificial hatching of trout is now carried on extensively, and lakes and streams can be stocked or replenished with fish if they are not too polluted.
The Bull Trout or Sea Trout (S. eriox) most resembles the salmon in appearance and habits, though thicker in proportion to its length, and with larger and more numerous dark spots on the gill-covers and scales.
The Salmon or White Trout (S. trutta) is a more elegant fish, and its flesh is much more delicate in flavor. The habits of both are similar.
The Rainbow Trout (Salmo irideus) of America has been introduced into many parts of the world; in New Zealand, especially in Lake Taupo, it attains the greatest size, many tons being caught yearly.
Whitefish (Coregonus clupeiformis), the common whitefish, is the largest of all the American lake whitefish. It is very highly esteemed for food, ranking, indeed, as one of the finest table fishes. Its range extends from Lake Champlain to the Arctic Circle.
Cartilaginous Fishes ( Elasmobranchii )
These fishes have a cartilaginous, pliant, undeveloped skeleton, and are not covered with true scales. They include rays, sawfish, sharks, skates and others.
Ray, a popular name applied to many of the flat cartilaginous fishes: Thornbacks, Electric Rays, Sting-rays, Eagle-rays are representative. They lead a somewhat sedentary life at the bottom of the sea, moving sluggishly by undulations of the pectoral fins which form a large part of the flat body. Many attain a large size, sometimes measuring six feet across.
Sawfish (Pristis) are distinguished by the prolongation of the snout into a formidable weapon bordered on each side by sharp teeth. Some species are found off the southern coasts of North America and in the Gulf of Mexico, and in the Mediterranean and many other seas. With its saw, which is sometimes six feet in length, the sawfish slashes or rips up its prey, and its assault is often fatal to large whales.
Sharks are a group of very simple fishes, which have only a cartilage skeleton, no bone being developed anywhere in them. They have the gill openings on the side of the neck separate, and in all of the common species the mouth is on the lower side of the head instead of at the tip, as in ordinary fishes. The tail has unequal lobes, the upper lobe being much the larger. There are always four paired fins and one or more on the back. The size of the sharks varies from the smaller dogfish, about two feet long, to the great basking shark, some forty feet in length. Most of these species are very voracious, but the tales of man-eating are often exaggerated, although occasionally they may occur. Some of the largest species feed exclusively on shellfish. The flesh of several species is good to eat, but they are mostly neglected in America. The livers are very rich in oil, which commands a good price for use in dressing leather. In some species the skin has small spines and was formerly used (it was called shagreen) instead of sandpaper. Skin with larger plates is sometimes used in the manufacture of pocketbooks, etc.
Skates (Raia batis).—A group of fishes, closely related to the sharks, but having the body flattened from above downward, and with the anterior fins so united to the side of the head and the body that it has a rhomboid appearance and the tail seems like an inconsiderable appendage. The mouth and the gill openings are on the under surface. The animals are bottom feeders, living on clams and mussels, buried in the mud. In Europe some of the smaller species are used for food. Another has a large electric battery on either side of the head, capable of giving very strong shocks. This is called the torpedo.
Armored Fish ( Ganoidei )
These include, among others, the Bony Pike and the Sturgeons.
Bony Pike or Garfish.—A remarkable genus of fishes inhabiting North American lakes and rivers, and one of the few living forms that now represent the order of ganoid fishes so largely developed in previous geological epochs. The body is covered with smooth, enameled scales, so hard that it is impossible to pierce them with a spear. The common garfish attains a length of five feet, and is easily distinguished by the great length of its jaws.
Sturgeon (Acipenser).—These large, sluggish fishes, some reach a length of over ten feet, and live on worms, crustacea, and mollusks. The body is long and narrow with five rows of bony shields. There are many species of sturgeon, all confined to the northern hemisphere. They live in the sea and great lakes, and ascend the great rivers. All supply valuable commodities, for which they are regularly captured on a large scale. These commodities are their flesh, which is palatable and wholesome, their roe (caviare), and their air-bladders, from which isinglass is made.
The most important sturgeon-fishery in Europe is that of the Volga and the Caspian Sea. The flesh of the fish is salted, and caviare and isinglass made on a large scale from the roes and air-bladder.
The Sterlet (A. ruthenus) is a much smaller species, which is common in the Black and Caspian Seas, and ascends the Danube as far as Vienna. It is one of the principal objects of the sturgeon fishery on the Volga.
In America sturgeon flesh is eaten fresh, and caviare is made both in Georgia and in San Francisco; but there is no great fishery in any particular district, and the manufacture of isinglass does not receive much attention. The sturgeon of the great lakes (A. rubicundus) and the Shovel-nose of the Mississippi valley are the chief American species.
Lung-Fishes or Double-Breathers ( Dipnoi )
are at present represented by three fresh-water types, the insignificant remnant of a group that was once dominant in the sea, and would have become entirely extinct if some of its members had not taken to live in the waters of the land. These types are the eel-shaped mud-fishes of West Africa (Protopterus) and South America (Lepidosiren), and a Queensland form (Ceratodus). In all these the swim-bladder has been converted into a regular lung, which returns purified blood to the heart. The African form lives in streams which are liable to dry up, and [229] were it not for the possession of a kind of lung capable of breathing air, it would perish during the dry season, whereas it remains embedded in the mud in a torpid state till the rains return.
The Queensland lung-fish lives under somewhat different conditions, for its native rivers do not entirely dry up, but are reduced to a series of deep holes connected by mere trickles of water. These holes become so foul from decaying vegetation and dead fish that the possession of a lung is a vital matter, and if the ceratodus were not able to come to the surface and breathe air it would probably succumb.